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Final Flight of AtlantisMoments before liftoff, the engines of the space shuttle Atlantis ignite, shooting out a plume of exhaust over the launch pad at NASA's Kennedy Space Center in Florida. Atlantis launched at 2:20 p.m. ET on May 14 carrying six astronauts, a new research module for the International Space Station, and replacement electronic equipment.

The shuttle landed Wednesday at Kennedy at 8:48 a.m. ET after a 12-day mission, bringing to a close the final scheduled flight for Atlantis."It certainly did strike me walking around the orbiter today that I probably just did the coolest thing I'll ever do in my life—and it's behind me," flight commander Kenneth Ham said today during a post-landing press briefing.

"It's great, and it's a great memory, but it's over."NASA plans to stop flying space shuttles by the end of the year, and just two launches remain on the slate. Discovery will fly in September, followed by Endeavour in November.With the Constellation program for a human return to the moon effectively canceled, the only way for U.S. astronauts to reach space after the shuttles have been retired will be with the Russian-run Soyuz program—unless private space travel takes off.

(See pictures from the previous shuttle mission, which was the next-to-last flight of Discovery.)

—Rachel Kaufman

Photograph courtesy NASA